Boiling up

[Enoch]

Here's a really daft idea - have you changed the routing of the water pump drive belt? If so is the pump turning the right way? If it was forcing water back against the wrong side of the stat then it would overheat with the stat in but would probably be ok with the stat out. By the same token - is the stat in the right way round?
Might sound daft but thought it worth asking.
Enoch.

[flyerncle]

Ash has hit it on the head as I posted previously,the small pipes in the drawing are returns to the top of the tank and if you have no water in the system returning it wont pump and what ever is close to the cylinders and top of the head will boil as it cant circulate.

It may be a different system to what I have seen previously on BM's so the bleeder may not be there.

[aerosam]

Originally Posted by Enoch

Here's a really daft idea - have you changed the routing of the water pump drive belt? If so is the pump turning the right way? If it was forcing water back against the wrong side of the stat then it would overheat with the stat in but would probably be ok with the stat out. By the same token - is the stat in the right way round?
Might sound daft but thought it worth asking.
Enoch.

No not daft at all, I have indeed re-routed the belt to remove the power steering pump, but it is still turning the same way.

Thankfully the stat is idiot-proof, only fits in the right way round, and only with the bleed valve at the top.

[aerosam]

Originally Posted by flyerncle

Ash has hit it on the head as I posted previously,the small pipes in the drawing are returns to the top of the tank and if you have no water in the system returning it wont pump and what ever is close to the cylinders and top of the head will boil as it cant circulate.

It may be a different system to what I have seen previously on BM's so the bleeder may not be there.

Ahhh, now I understand! Ok so what i need to do is unplug the 1 heater port and route it to the other, then use a T-piece to tap off to the header tank? is that right? That should restore flow round what was the heater circuit. I can't take it to the top of the tank as there's nowhere for it to go.

pipe 11 is definitely an overflow as it simply flowed down to the underside of the car on the donor, pipe 6 was connected to a small port next to the rad top hose on the donor - but my new rad has no such port I assumed that they were both overflows as the header tank cap has 2 o rings with a 1/4" gap between each which allows water to flow to either of the 2 pipes. It's not shown on the drawing at all.

I can't remember if the donor had a bleeder, and the drawing doesn't show that much detail

[aerosam]

Ok, had a guts full fo this thing now.

replumbed the water rail to allow the heater circuit to flow, which it did nicely. Got all the air out, ran it and guess what, the f***ing thing boiled up -AGAIN!

Just pulled out the brand new stat and put it in a pan of boiling water, after a minute or so at a rolling boil - it opened about 2mm - surely this isn't enough? I'm gonna drill a couple of holes in it now and put it back in. it cost me £50 but f*** it i'm all out of other options.

one pissed off builder.

[CTWV50]

Could it be a headgasket? You can get a sniffer test called a block tester, and it sniffs for carbon monoxide in the header tank steam. Search ebay they are about 20-30 quid.

Edit: oh a bit more expensive!

http://cgi.ebay.co.uk/UNIVERSAL-CYLI...#ht_1134wt_907

[flyerncle]

Ask friendly mot tester to sample header tank for HC as there should not be unburnt fuel in it,if there is the head gasket is donald ducked.

[aerosam]

Ok, calmed down a little now - drilled 2x 4mm holes in it and refitted the stat, refilled and bled the system, started it up. Water flowed through the rad and it got hot within a couple of mins. Water temp rose to about 65 degrees and seemed to stay there, after 5 mins i shut it off.

No boiling in the header tank but definite bubbling noises coming from somewhere for a few seconds. ???

removed the sump plug to drain the oil while it's hot - will go back to it tomorrow now.

[flyerncle]

Is the total rad hot from top to bottom after the stat opens,I still think the problem is flow to header related,one way or the other it needs to go back to the highest point.

Bin the B EM one and start again with a ford or vag one as they have top returns and feed from the bottom of the tank.

Water fed to bottom hose and tee into top hose to bleed return to top of tank.

[aerosam]

Originally Posted by flyerncle

Is the total rad hot from top to bottom after the stat opens,I still think the problem is flow to header related,one way or the other it needs to go back to the highest point.

Bin the B EM one and start again with a ford or vag one as they have top returns and feed from the bottom of the tank.

Water fed to bottom hose and tee into top hose to bleed return to top of tank.

Yeah the rad is hot throughout seems to be ok now

Here's how it looks now, sorry for the huge pic.



I've got it plumbed like this as it's the closest I can get it to how the donor was set up. I'm not going to be able to work on it again now till Sunday but then i'll give it another long run and see how the temperature control works when the cooling fan kicks in. (so far it hasn't as the switch is in the rad bottom hose)

I'll pop to a scrappie on Saturday and see what I can lay my hands on as a new header tank with a flow through.

I don't quite follow "Water fed to bottom hose and tee into top hose to bleed return to top of tank" can you expand a little?

Thanks for all you help.